1. Field of the Invention
The present invention is broadly concerned with improved metal-containing bodies having a surface presenting metal surface atoms, with at least some of the metal atoms being directly chemically bonded with non-naturally occurring heterologous protective groups and especially phosphate groups in the absence of metal oxide between the metal atoms and the protective groups, so as to provide a novel, stable protective film rendering the metal surface resistant to corrosion and the like. More particularly, the invention pertains to protected bodies of this type, as well as a method of producing the same, wherein the surface metal atoms are selected from the group consisting of the first and second row of transition metals, the rare earth metals, Hf, Ta, W, Re and the metals of Group III (preferably Al and Fe) and wherein a non-naturally occurring phosphate layer is directly bonded to such metal atoms and having a thickness of from about 20-100 .ANG..
2. Description of the Prior Art
Nearly every metal known (with the exception of gold) reacts in the atmosphere to form a naturally occurring oxide surface film, usually in combination with outer surface layers of hydroxide or bound molecular water. If a metallic surface bearing such an oxidized film is scratched or the oxidized film is removed in some other fashion, the metal will immediately reoxidize in air.
There have been many studies of corrosion films formed on metal surfaces, especially in the case of thick corrosion films that can be analyzed by bulk surface techniques. Other studies using ultra-high vacuum surface analysis probes have examined the role of corrosion inhibitors in modifying oxide surface films. Thus a body of literature exists regarding corrosion inhibitors which detail the changes resulting from potentially corrosion-inhibiting treatments or the formation of protective films over the naturally occurring oxide films. Phosphate treatments have a long history of effective action as corrosion inhibitors, but in all cases the phosphate treatments are applied over naturally occurring oxides, or at least have such oxides as intermediaries between the metal surface atoms and the phosphate protectants.